Overswing when deflected from its position. Radial arms or vanes attached to the card dampen the swing of the needle. This type of compass is mounted horizontally, and is read through a glass cover on the top. The compass consists primarily of a cylindrical metal bowl filled with compass fluid.
In the center of the bowl is a semi-float type card to which are attached the magnetized needles and the radial arms. The card is marked with the four cardinal points, with an arrow indicating North.
Inside the bowl, a fixed mark acts as the lubber's line. A graduated rotatable ring (verge), with two clamping screws, is fastened to the upper edge of the compass bowl. Across the inside of the ring are two horizontal, parallel white wires, spaced equally on either side of the N and S markings. In making readings, the ring is turned until the two white wires are parallel to the North-South lines on the card. The airplane heading is read as the marking on the ring which is directly above the lubber's line.
A box containing magnets which may be turned to compensate for deviation is located on the bottom of the compass. Measures 7 inches diameter and 4 inches in height. Much of this information was copied but I believe accurate. Feel free to ask questions.This item is in the category "Collectibles\Militaria\WW II (1939-45)\Original Period Items\United States\Field Gear, Equipment". The seller is "stardom" and is located in this country: US. This item can be shipped to United States.